Sulfidated　nanoscale　zero-valent　iron　(S-NZVI)　has　strong　reactivity　and　electron　selectivity　and　is　one　of　the　promising　remediation　materials　in　the　field　of　ground　water　remediation.　Due　to　the　easy　aggregation　of　the　material,　its　reactivity　is　reduced,　limiting　the　application　in　environmental　remediation.　In　this　paper,　the　zeta　potential　(zeta)　of　S-NZVI　at　different　pH　and　the　electrophoretic　mobility　of　S-NZVI　coated　with　sodium　alginate　(SA-S-NZVI)　at　different　ionic　strengths　were　investigated.　The　thickness　of　the　polyelectrolyte　layer　and　the　surface　charge　of　sodium　alginate　were　also　calculated　by　combining　the　soft　particle　theory.　The　polyelectrolyte　layer　properties　were　correlated　with　the　particle　dispersion　to　study　the　particle　properties.　The　results　showed　that　the　thickness　of　the　coating　layer　increased　with　the　concentration　of　sodium　alginate,　and　the　settling　rate　and　aggregation　rate　decreased.　Thus　the　stability　of　the　particles　increased.　Combined　with　the　XDLVO　theory,　although　the　polyelectrolyte　layer　increases　the　surface　potential　of　S-NZVI　and　improves　the　electrostatic　repulsion,　the　spatial　effect　plays　a　significant　role　in　the　total　repulsion　energy.　The　smaller　the　particle　size　of　SA-S-NZVI,　the　weaker　the　magnetism.　Therefore,　the　thicker　the　polyelectrolyte　layer,　the　better　the　stability　of　the　particles.　Finally,　the　change　of　particle　size　with　time　was　predicted　by　the　Smoluchowski　aggregation　model.　This　study　has　a　significant　effect　on　the　sedimentation　process　of　water　treatment,　the　problem　of　filter　clogging　of　drinking　water,　and　the　problem　of　aquifer　blockage　in　the　infiltration　process　of　surface　water.